Mechanical strength and electrical conductivity of reactively-sintered pseudobrookite-type Al2TiO5–MgTi2O5 solid solutions

Al2TiO5–MgTi2O5 solid solutions were synthesized by reactive sintering of α-Al2O3, TiO2 anatase and MgCO3 (basic) powders at 1400°C (and at 1300°C for some composition) for 2 h, with changing the MgTi2O5 ratio to form the composition of Al2(1−x)Ti1+xMgxO5 (x = 0.0–1.0) and evaluated their properties. With increasing MgTi2O5 molar ratio, the matrix Al2TiO5–MgTi2O5 grains became more anisotropic, and the coefficient of thermal expansion increased due to the decrease of microcracks. Al0.2Ti1.9Mg0.9O5 (x = 0.9) showed the maximum strength of 47.9 MPa. On the other hand, MgTi2O5 (x = 1.0) showed low bending strength of 13.2 MPa due to the grain growth during the sintering at 1400°C. Al0.6Ti1.7Mg0.7O5 (x = 0.7) sintered at 1300°C indicated the highest conductivity. The conductivity of pseudobrookite-type ceramics strongly depends on microcracks.